patch 8.2.3507: generating proto files may fail

Problem:    Generating proto files may fail.
Solution:   Define __attribute().
diff --git a/src/version.c b/src/version.c
index a4a2363..ceb50ea 100644
--- a/src/version.c
+++ b/src/version.c
@@ -758,6 +758,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3507,
+/**/
     3506,
 /**/
     3505,